<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2.5.17/dist/vue.js"></script>
</head>
<body>
    <div id="app">
        <input type="text" v-model="msg">
        <p>{{reverseMsg}}</p>
    </div>
</body>
<script>
    const app = new Vue({
        el:"#app",
        data:{
            msg:""
        },
        computed:{
            reverseMsg(){
                return this.msg.split("").reverse().join("");
            }
        }
    })
</script>
</html>